Visual Pathways Flashcards

(32 cards)

1
Q

Main Visual pathway:

A

GCs>optic nerve>chiasm>LGN>optic radiations>visual cortex

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2
Q

intrinsically photosensitive ganglion cells contain?

A

melanopsin

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3
Q

2 targets of melanopsin?

A
  1. suprachiasmatic nucleus: circadian

2. pretectal n.: midbrain: pupil response

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4
Q

M ganglions detect? what %?

A

motion: 10%

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5
Q

P ganglions detect?

A

colour/visual acuity: 80%

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6
Q

target of most GCs?

A

lateral geniculate nucleus in the thalamus

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7
Q

what happens in superior colliculus?

A

eye movements

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8
Q

what happens in suprachiasmatic n.?

A

circadian rhythm

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9
Q

what happens in pretectum midbrain?

A

pupil responses

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10
Q

what crosses at optic chiasm?

A

nasal fibres of optic nerve which sense the temporal fields

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11
Q

right visual hemisphere viewed by?

A

left cortex

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12
Q

left visual hemisphere viewed by?

A

right cortex

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13
Q

what usually causes problems in the optic chiasm?

A

pituitary or internal carotid issues

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14
Q

what does the medial geniculate nucleus receive?

A

hearing signals

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15
Q

how many layers of LGN? divided into which two?

A

Magnocellular: 1,2 (darker, bigger)
Parvocellular: 3,4,5,6

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16
Q

Which layers in the LGN receive from which eye?

A

Right:2,3,5
Left:1,4,6

17
Q

what happens to signal after LGN ?

A

project as optic radiation to cortex via massive white matter tracts

18
Q

primary visual cortex is where?

A
  1. area 17

2. occipital lobe around calcarine fissure

19
Q

centre of the visual field is where in the lobe?

A

most occipital part of the visual cortex

20
Q

unilateral vision loss lesion is most likely?

A

before the optic chiasm

21
Q

bitemporal vision loss lesion is most likely?

22
Q

bilateral field loss, lesions is most likely?

A

after the chiasm

23
Q

when do you get macular sparing?

A

unique feature of vascular problem in the visual cortex

24
Q

how many intrinsically photosensitive ganglion cells per retina?

25
intrinsically photosensitive ganglion cells contain what?
melanopsin: like in invertebrates
26
what happens when melanopsin is hit with light?
depolarizes intrinsically photosensitive ganglion cells
27
what non vision info do intrinsically photosensitive ganglion cells transmit? 5 things:
1. circadian rhythm (hypothalamus) 2. sleep regulation 3. pupil responses 4. general light levels 5. light allodynia
28
photophobia during migraine comes how?
pain signals from dura via trigeminal end up at posterio nucleus of thalamus and intrinsically photosensitive ganglion cells also project there
29
blind people who have retinas get photophobia?
yes
30
Pupil response pathway
optic nerve>pretectal nucleus>edinger-westphal>CNIII>sphincter pupillae
31
where do intrinsically photosensitive ganglion cells with melanopsin project to in the pupil repsonse?
optical pretectal nucleus
32
where is suprachiasmatic nucleus?
hypothalamus, and affected by intrinsically photosensitive ganglion cells